JP2011012691A - Resin pipe joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin pipe joint compatibly achieving pull-off resistance and good sealing performance while economically comprising two members, namely, a joint body and a union nut.SOLUTION: The resin pipe joint includes a fluororesin joint body 1 with an inner cylinder 4, a male screw 5, a circumferential groove m, and a protrusion 23 raised from a straight barrel cylinder part 4B in a radially outward direction, and a fluororesin union nut 2 with a female screw 8, a first pressing part 10 pressing an enlarged diameter part 3A, and a pressing inner peripheral part 13. By fastening the union nut 2 in a condition in which the enlarged diameter part 3A is formed by inserting a tube 3 in the inner cylinder 4, the pressing inner peripheral part 13 is press-contacted and externally fitted in an enlarged diameter straight part 12 into which the protrusion 23 bites from the inner peripheral surface side, and a small-diameter side end part of an enlarged diameter changing region 9 is pressed by a pressing part 10 for sealing.

Description

  The present invention relates to a resin pipe joint having a structure in which a tube as a fluid transfer path is expanded (flared) and connected, and more specifically, in various technical fields such as semiconductor manufacturing, medical / pharmaceutical manufacturing, food processing, chemical industry, etc. It is also suitable for piping of high-purity liquid and ultrapure water handled in the manufacturing process, and relates to a resin pipe joint used as a connecting means of a tube that is a fluid device such as a pump, a valve, a filter, or a fluid transfer path. .

  As this type of resin pipe joint, a tube joint disclosed in Patent Document 1 is known. That is, the tube 1 made of a synthetic resin is forcibly pushed into the inner tube portion 5 of the joint body 4 or the tube end portion 2 is expanded in diameter as shown in FIG. It fits in part 5. Then, the union nut 6 fitted in the tube in advance is screwed into the joint body, and is tightened to forcibly move in the axial direction of the joint body 4, so that the enlarged root portion 2 a of the tube 1 is edged. This is a structure in which the portion 6 a is pressed strongly in the axial direction to seal between the tube 1 and the inner cylinder portion 5.

  As the structure similar to the above-described structure, the one disclosed in FIGS. 8 and 9 of Patent Document 2 and the resin pipe joint disclosed in FIG. 6 of Patent Document 3 are known. As described above, the joint structure in which the tip of the tube is expanded (flared), fitted to the joint body, and fastened with a nut is the structure disclosed in FIG. 5 of Patent Document 2, FIG. 5 of Patent Document 3, and the like, Compared to a three-part tube fitting in which the tube end, which is externally expanded on the inner ring of the dedicated part, is fitted into the tubular receptacle of the joint body and fastened with a union nut, the joint body and union nut are fewer parts There is an advantage that a good sealing function can be obtained while economically constituting a pipe joint with two points.

  However, in the conventional resin pipe joint composed of two parts as described above, the tube end is expanded and firmly fitted, and the expanded root portion is tightened with a union nut. There was a tendency for the force to pull out the tube from the joint body to be relatively weak, probably because it was for the purpose of functioning. Although the tube itself is pulled out and moved, there is also a problem that the sealing point due to the pressing of the edge portion is also shifted and the sealing performance is adversely affected. In particular, when the resin pipe joint is formed of a resin material having a large expansion coefficient such as a fluororesin so as to handle a high temperature fluid of 100 ° C. or higher, those problems become more prominent.

  Therefore, as disclosed in Patent Document 4, a drawing-proof means having a structure in which a C-shaped split ring is interposed between the tube enlarged portion and the union nut in a state of being fitted in the circumferential groove of the tube enlarged portion. It is known to provide a resin pipe joint that is strong not only for the sealing function but also for pulling out the tube. However, the resin pipe joint disclosed in Patent Document 4 requires a pre-treatment for forming a circumferential groove in the tube enlarged portion in advance, and the number of parts is increased to 3 parts. A new problem arises that the economic efficiency is impaired. Therefore, there is still room for further improvement in making the resin pipe joint consisting of the joint body and the union nut strong against pulling out without causing new problems. .

Noto 3041899 gazette Japanese Patent Laid-Open No. 7-27274 JP 2002-357294 A Noto 2587449 gazette

  In view of the above circumstances, an object of the present invention is a resin pipe that can achieve both a pull-out resistance and a good sealing property while being economical, consisting of a joint body and a union nut. The point is to provide a joint.

According to the first aspect of the present invention, in the resin pipe joint, the end portion of the synthetic resin tube 3 is expanded and the inner tube portion 4 that can be externally fitted and the inner tube portion 4 of the tube 3 are externally fitted. A joint body made of a synthetic resin, which includes a protrusion 23 that protrudes radially outward from the straight cylinder portion 4B having a constant diameter in the inner cylinder portion 4 and a male screw 5 so as to be able to bite into the expanded diameter portion 3A. 1 and
A female screw 8 that can be screwed into the male screw 5, a first pressing portion 10 for sealing that can act on a small-diameter side portion of the diameter-enlarged change region 9 in the enlarged-diameter portion 3A, and the straight body in the enlarged-diameter portion 3A A union nut 2 made of a synthetic resin including a presser inner peripheral portion 13 that can be fitted onto the diameter-enlarged straight portion 12 surrounded by the cylindrical portion 4B;
The shaft of the joint body 1 of the union nut 2 in which the female screw 8 is screwed into the male screw 5 in a state where the tube 3 is fitted on the inner cylinder portion 4 to form the enlarged diameter portion 3A. Due to the screwing in the direction of the center P, the presser inner peripheral portion 13 is press-fitted to the diameter-enlarged straight portion 12 surrounded by the projection 23, and the small-diameter side portion of the diameter-enlargement change region 9 is The first pressing portion 10 is configured to be pressed in the axial center P direction.

  The invention according to claim 2 is the resin pipe joint according to claim 1, wherein the presser inner peripheral portion 13 has no radial gap between the presser inner peripheral portion 13 and the enlarged straight portion 12, and the union nut 2 The diameter-enlarged straight portion 12 is press-fitted and externally fitted to the extent that the enlarged-diameter portion 3A is not rotated by the tightening.

  According to a third aspect of the present invention, in the resin pipe joint according to the first or second aspect, the diameter of the upper surface 24 in the tube insertion direction of the protrusion 23 increases toward the lower side in the tube insertion direction. It is formed on a forwardly inclined surface, and the lower surface 25 is formed on an upright surface in the tube insertion direction.

  According to a fourth aspect of the present invention, in the resin pipe joint according to any one of the first to third aspects, the protrusion 23 is formed in an annular shape continuous around the axis P. It is what.

  According to a fifth aspect of the present invention, there is provided the resin pipe joint according to any one of the first to fourth aspects, wherein the joint main body 1 has a retaining action that can act on the large-diameter side portion of the diameter-enlarged region 9. The second pressing portion 11 is formed, and the large-diameter side portion of the enlarged diameter changing region 9 is pressed by the second pressing portion 11 in the axis P direction by the screwing of the union nut 2. It is characterized by being comprised.

  According to a sixth aspect of the present invention, in the resin pipe joint according to the fifth aspect, after the union nut 2 is screwed, the first pressing portion 11 starts pressing the large-diameter side portion. The pressing portion 10 is set in a state where pressing of the small diameter side portion is started.

  The invention according to claim 7 is the resin pipe joint according to any one of claims 1 to 6, wherein both the joint body 1 and the union nut 2 are made of a fluororesin.

  According to the first aspect of the present invention, as will be described in detail in the section of the embodiment, since the first pressing portion presses the small diameter side portion of the diameter expansion change region, the seal portion is formed at the tip portion of the inner cylinder portion. As a result, the tube and the joint main body are satisfactorily sealed without the fluid entering between the inner cylinder portion and the enlarged diameter portion. Because the diameter-enlarging straight part fitted on the inner cylinder part is pressed against the outer peripheral surface of the straight cylinder part and the inner circumference part of the presser foot, it can strongly resist the pulling force, and it can be attributed to the pulling force. Due to the structure in which the diameter-expanded straight part is enlarged, it is also prevented from shifting in the axial direction by expanding and deforming in the radial direction, and the enlarged diameter part is prevented from moving in the axial direction. A function that effectively restricts the movement in the direction of exiting from the tube portion is generated.

  And the diameter-enlarging straight part fitted on the inner cylinder part is pressed against the outer peripheral surface of the straight cylinder part and the inner circumference part of the presser, so there is no escape area (expansion deformation cannot be performed), and the pressing force is strengthened. In addition to being firmly held, the protrusions bite into the enlarged diameter straight part from the inner peripheral surface side, so the action of preventing the enlarged diameter part from moving out of the inner cylinder part in the axial direction is strengthened, The pull-out force is further improved. As a result, it is possible to provide a resin pipe joint that is economical and consists of two points of a joint body and a union nut, and that can achieve both resistance to pulling out and good sealing performance. .

  According to the second aspect of the present invention, the union nut does not rotate with the enlarged diameter portion due to tightening, and does not cause inconveniences such as a shift of the seal point and a decrease in the pull-out resistance due to the rotational movement of the enlarged diameter portion. However, there is an advantage that the diameter expansion straight portion can be firmly sandwiched and fixed between the straight barrel portion and the inner circumferential surface of the presser, and the pull-out force can be further improved.

  According to the invention of claim 3, it becomes easy to insert and fit into the straight barrel portion over the tube projection by the inclined upper side surface, and over the tube projection by the standing lower side surface. Thus, there is an advantage that the tube can be held more firmly because it is difficult to perform the extraction movement, that is, the extraction movement from the inner cylinder.

  According to invention of Claim 4, since a projection part is a cyclic | annular thing which continues in the circumferential direction, a tube is inserted over a protrusion part over the perimeter, and the invention by any one of Claims 1-3 There is an advantage that the effect is enhanced.

  According to the fifth aspect of the present invention, since the second pressing portion presses the large-diameter side portion of the diameter expansion change region in a state where the presser inner periphery is press-fitted and fitted to the diameter-enlarging straight portion, the union nut is tightened. Along with this, a preferable action of positively pushing the enlarged diameter straight part into the inner back side also occurs, and there is an effect that contributes to more firmly inserting the tube into the back. And, since the tube cannot easily move inward due to the press-fitting outer fit of the inner periphery of the presser foot, the action of increasing the thickness of the diameter-enlarging straight portion by the pressing of the second pressing portion is born. As a result, the diameter-enlarging straight portion is more firmly sandwiched between the straight barrel portion and the inner circumferential portion of the presser, and the pull-out resistance can be further improved.

  According to the invention of claim 6, since the pressing of the small-diameter side portion by the first pressing portion is started after the pressing of the large-diameter side portion by the second pressing portion is started, the diameter is expanded by the tightening operation of the union nut. The action of pushing the straight portion into the inner tube side of the inner tube portion occurs, and the straight tube portion can be inserted into the inner tube more securely.

  According to the invention of claim 7, since both the joint body and the union nut are formed of a fluorine-based resin having characteristics excellent in chemical resistance and heat resistance, even if the fluid is a chemical liquid or a chemical liquid, Or even if it is a high-temperature fluid, a joint structure part does not deform | transform and it becomes easy to leak, and favorable sealing property and drawing-out force can be maintained now. Note that the fluorine-based resin is preferable in that it is stable at high temperatures, excellent in water repellency, has a small coefficient of friction, has extremely high chemical resistance, and has high electrical insulation. Further, if the joint body and the union nut are formed of the same fluororesin material, the linear expansion coefficients are also the same, and there is an advantage that the sealing performance at high temperature is improved.

Sectional drawing which shows the structure of the resin pipe joint by Example 1 FIG. 1 is an enlarged sectional view showing the main part of FIG. Enlarged sectional view of the main part showing the relative positional relationship between the peripheral edges for sealing and retaining Chart showing the pull-out force test results from the inner tube of a standard tube

  Embodiments of a resin pipe joint according to the present invention will be described below with reference to the drawings. The “inner back side” in the present specification is a definition of the back side in the direction of the axis P from the reference part (or part), and the axis in the object (eg, joint body 1). The central position in the direction of the heart P is not necessarily the deepest.

[Example 1]
As shown in FIGS. 1 and 2, the resin pipe joint A according to Example 1 includes a tube 3 made of a fluororesin (an example of a synthetic resin typified by PFA, PTFE, etc.), a fluid device such as a pump and a valve, A joint body 1 made of fluororesin (an example of a synthetic resin typified by PFA, PTFE, etc.) and a fluororesin (synthetic resin typified by PFA, PTFE, etc.) are connected to tubes of different diameters or the same diameter. An example) It is comprised by two parts with the union nut 2 made from. 1 and 2 show an assembled state in which the union nut 2 is tightened by a predetermined amount.

  As shown in FIGS. 1 and 2, the joint main body 1 has an inner cylinder portion 4 at one end that can be fitted and expanded by expanding the end portion of the tube 3, and the outer peripheral side of the inner back side portion of the inner cylinder portion 4. A cylindrical space having a cover cylinder portion 6 having a circumferential groove m extending in the direction of the axis P to allow entry of the tip of the tube 3 expanded in diameter, a male screw portion 5 made of a trapezoidal screw, and an axis P It is formed in the cylindrical member provided with the fluid path 7 of a shape. The inner cylinder part 4 has a straight shape having a tip tapered cylinder part 4A for gradually expanding the diameter of the tube 3 and a straight cylinder part 4B formed on the large diameter side of the tip tapered cylinder part 4A. It is structured as a thing.

  In the circumferential groove m, the outer peripheral surface that is the inner peripheral surface of the diameter is the outer peripheral surface 4b of the straight barrel portion 4B, and the outer peripheral surface that is the outer peripheral surface of the diameter is the inner peripheral surface 6a of the cover cylindrical portion 6. . A joint flange 1A is formed at a position away from the inner peripheral surface 21 of the circumferential groove m in the axial center P direction by a predetermined length, and the outer peripheral surface of the end portion of the cover cylinder portion 6 from the substantially root portion of the joint flange 1A. A male screw portion 5 is formed over the entire area. The tip surface of the inner cylinder part 4 is formed with a reverse taper angle that is closer to the inner inner side (the inner side in the direction of the axis P) toward the inner side in the radial direction. The shape of the liquid reservoir peripheral portion 17 due to the inner peripheral surface of the tube 3 being expanded and displaced toward the enlarged diameter portion (flare portion) is defined as the inner peripheral side expanded shape, and the fluid is stored in the liquid peripheral portion. 17 is difficult to stay. The cut surface 16 is formed so that the maximum diameter thereof is a substantially intermediate value between the inner diameter and the outer diameter of the tube 3 in the natural state, but this is not particularly concerned.

  A protruding portion 23 is formed on the straight barrel portion 4B on the side of the tip portion of the cylindrical portion 4A that protrudes radially outward so as to be able to bite into the enlarged diameter portion 3A. The projecting portion 23 is an annular one that is continuous around the axis P, and the upper surface 24 in the tube insertion direction is formed as a forwardly inclined surface that increases in diameter toward the lower side in the tube insertion direction. The lower surface 25 in the tube insertion direction is formed as an upright vertical surface perpendicular to the axis P, and has an outer peripheral surface 26 parallel to the axis P between the upper side 24 and the lower side 25, The cross section has a substantially trapezoidal shape. In other words, the inclined upper side surface 24 makes it easy to insert and fit into the straight barrel portion 4B over the protruding portion 23 of the tube 3, and the raised lower side surface 25 gets over the protruding portion 23 of the tube 3. It is configured so that it is difficult for all the extraction movements to be performed.

  As shown in FIGS. 1 and 2, the union nut 2 includes an internal thread portion 8 that can be screwed into the external thread portion 5, and an expanded diameter changing region 9 in an expanded diameter portion 3 </ b> A that is externally fitted to the inner cylindrical portion 4 of the tube 3. Peripheral edge for sealing (an example of a first pressing portion) 10 that can act on a small diameter side end portion (an example of a “small diameter side portion”) and a large diameter side end portion (an “large diameter side portion”) And an outer diameter fitting straight edge 12 surrounded by a straight barrel portion 4B having a constant diameter in the enlarged diameter portion 3A. A possible presser inner peripheral part 13 and a guide cylinder part 14 that surrounds the tube 3 over a predetermined length in the axis P direction following the sealing peripheral edge 10 are formed.

  The sealing peripheral edge 10 has an inner diameter substantially equal to the outer diameter of the tube 3, and the pressing surface 10 a is a side peripheral surface orthogonal to the axis P. The circumferential edge 11 for retaining is larger in diameter than the outer peripheral surface 4b of the straight barrel portion 4B, which is the maximum diameter of the inner cylindrical portion 4, and the thickness of the tube 3 is added. Although it is set to a value smaller than the diameter, that is, the diameter of the presser inner peripheral portion 13, it may not be (for example, smaller than the outer peripheral surface 4 b), and may act on the larger diameter side portion of the diameter expansion change region 9. It ’s fine. The pressing surface 11a of the retaining peripheral edge 11 is also a side peripheral surface orthogonal to the axis P.

  The presser inner peripheral portion 13 has no radial clearance between the presser inner peripheral portion 13 and the enlarged diameter straight portion 12 so that the enlarged diameter portion 3A is not rotated by tightening of the union nut 2. The retaining means N is configured to be set to a value that is press-fitted (press-fit externally fitted). This is because when the union nut 2 is tightened, the retaining peripheral edge 11 presses the enlarged diameter straight portion 12 in the axial direction so as to prevent the tube 3 from being pulled out. This is to prevent the portion 12 from escaping so as to swell outward in the radial direction, and to increase the pull-out force by cooperating with the peripheral edge 11 for retaining.

  Next, in order to externally insert and insert the end of the tube 3 into the inner cylinder portion 4, the tube 3 is forcibly pushed in at room temperature to expand the diameter, or it is easily heated and expanded using a heat source. Then, the protrusion 23 is pushed in, or the tube end is expanded in advance using a diameter expander (not shown), and then pushed into the inner cylinder portion 4 as shown in FIG. Insert the tube end 3t until the tube end 3t is located inward of the end wall 15 of the cover tube 6. As shown in FIGS. 1 and 2, the enlarged-diameter portion 3A that is externally fitted to the inner cylinder portion 4 includes an enlarged-diameter changing region 9 that is fitted on the outer peripheral surface 4a of the cylindrical portion 4A. It consists of the diameter-expanded straight part 12 fitted on the outer peripheral surface 4b of the barrel part 4B.

  That is, as shown in FIGS. 1 and 2, the joint main body 1 is formed by tightening the union nut 2 by screwing the female screw portion 8 with the male screw portion 5 in a state in which the tube 3 is externally fitted to the inner cylinder portion 4. Is screwed in the direction of the axis P, so that the presser inner peripheral portion 13 is externally fitted to the diameter-enlarging straight portion 12 that is surrounded by the projecting portion 23, and the inner cylinder in the large-diameter side portion of the diameter-enlarging change region 9 A portion having a diameter larger than the diameter of the portion 4 is pressed in the axial center P direction by the retaining peripheral edge 11, and a small diameter side portion of the diameter expansion change region 9 is pressed in the axial center P direction by the sealing peripheral edge 10. It is set to be pressed. Note that the diameter of the fluid transfer path 3W of the tube 3 and the diameter of the fluid path 7 are set to be the same diameter in order to obtain a smooth fluid flow, but may be different from each other.

  In this case, as described above, there is no gap in the radial direction between the presser inner peripheral portion 13 and the enlarged diameter straight portion 12, and the enlarged diameter straight portion 12 is provided between the straight barrel portion 4B and the presser inner peripheral portion 13. It is in the state where it is clamped. Moreover, in Example 1, the diameter-expansion change area | region 9 of the tube 3 is formed as a part which the front-end | tip narrows and covers 4 A of cylinder parts. The diameter expansion change region 9 is a state of a taper tube that gradually expands, and the sealing peripheral edge 10 and the retaining peripheral edge 11 are in a positional relationship apart from each other in the axis P direction, but the tip tapered tube As the angle of the outer peripheral surface 4a of the portion 4A with respect to the axial center P becomes steeper, the distance in the axial center P direction between the sealing peripheral edge 10 and the retaining peripheral edge 11 becomes closer. Further, the sealing peripheral edge 10 and the inner cylinder portion 4 are slightly separated from each other in the direction of the axis P (see FIG. 2 and the like). However, if the angle of the outer peripheral surface 4a becomes steep, the distance is increased. If it becomes loose, the separation distance is reduced. In a predetermined assembly state (see FIGS. 1 and 2) in which the union nut 2 is tightened (see FIGS. 1 and 2), the protruding portion 23 is configured to be positioned on the radially inner side of the presser inner peripheral portion 13.

  As shown in FIGS. 1 and 2, in a predetermined assembled state of the resin pipe joint A, the sealing peripheral edge 10 has the small diameter side end portion of the diameter expansion change region 9 of the tube 3 in the axis P direction. Since the pressing is performed, the small diameter side end of the outer peripheral surface 4a of the diameter expansion change region 9 and the inner peripheral surface of the tube 3 in contact with the portion are strongly pressed to form the seal portion S. The tube 3 and the joint main body 1 are well sealed by the seal portion S at the tip of the inner tube portion 4 without any fluid such as cleaning liquid or chemical solution entering between the inner tube portion 4 and the enlarged diameter portion 3A. Yes.

  The diameter-enlarging straight portion 12 that is press-fitted externally into the inner cylinder portion 4 so as to get over the protrusion 23 and bulge outward is formed on the straight cylinder portion 4B and the presser inner peripheral portion 13. The bulging portion that is forcibly surrounded by the protrusion 23 is pressed so as to be compressed inward, and is first held so as not to be deformed by expansion. It is located so as to bite into the enlarged diameter straight portion 12. As a result, the catch of the retaining peripheral edge 11 that pushes the large diameter side end portion of the diameter expansion change region 9 so as to substantially bite into the diameter expansion straight portion 12, and the protrusion 23 on the diameter expansion straight portion 12. By biting in from the inside of the diameter, the pulling force acting on the enlarged diameter portion 3A can be strongly resisted. In addition, the diameter-enlarging straight portion 12 can be prevented from sliding in the direction in which the diameter-enlarged portion 3A is pulled out due to the expansion force being able to expand and deform in the radial direction by the pulling force with the circumferential edge 11 for retaining as a base point. It also becomes.

  If the diameter-enlarged portion 3A is displaced in the axial center P direction even a little, the seal point in the seal portion S may be shifted and the seal function may be uncertain, but this is prevented in advance. Therefore, the retaining means N in which the movement in the direction in which the diameter-enlarged portion 3A is pulled out from the inner cylinder portion 4 in the direction of the axis P is firmly restricted is configured, thereby realizing an excellent pull-out resistance. As a result, the flare-type resin pipe joint A composed of the joint body 1 and the union nut 2 can be easily assembled by a nut operation in a state where the tube is mounted on the inner cylinder portion, and has excellent assemblability. Thus, it has been realized as an improved structure that can achieve both excellent sealing performance by the seal portion S and excellent pull-out resistance by the retaining means N.

  In addition, after the pressing of the large-diameter side portion of the enlarged-diameter changing region 9 by the retaining peripheral edge 11 is started, the pressing of the small-diameter side portion of the enlarged-diameter changing region 9 by the sealing peripheral edge 10 is started. Depending on the setting, that is, the pressing time difference means, there are the following operations and effects. That is, as shown in FIG. 3, when the union nut 2 is turned and tightened (screwed), first, the retaining peripheral edge 11 is first moved to the diameter expansion change region 9 (specifically, the diameter expansion change region). 9 at that time, the sealing peripheral edge 10 has not yet reached the diameter expansion change region 9. As a result, only the retaining peripheral edge 11 pushes the large-diameter side portion of the expanded diameter change region 9, more specifically, the portion having a larger diameter than the straight barrel portion 4 </ b> B in the axial center P direction. By the tightening operation, an action of trying to push the enlarged diameter straight part 12 into the inner inner side of the inner cylinder part 4 occurs.

  The diameter-enlarging straight portion 12 that is press-fitted and fitted to the straight barrel portion 4B is also pressed against the inner circumference portion 13 of the presser, but when the pressure-contact force is relatively weak, the inner-diameter portion is moved by shifting the diameter-expanding portion 3A. 4 to insert the tube into the joint body 1 more reliably, or in addition to this, the enlarged diameter straight portion 12 pushed in the axis P direction moves in the axis P direction. Therefore, it is possible to obtain a preferable effect that the pressure contact force is further increased and the pinch is firmly held in an attempt to expand in the radial direction due to difficulty. When the pressure contact force is relatively strong, the diameter-enlarging straight portion 12 pushed in the direction of the axis P does not move in the direction of the axis P first, thereby causing a strong action to expand in the radial direction. And the pressurizing inner peripheral portion 13 can obtain an effect that the enlarged diameter straight portion 12 is more firmly held.

  Moreover, when it comes to the situation where the projection part 23 which is a circumferential protruding item has stabbed into the diameter expansion straight part 12, physical movement of each diameter part 3A becomes still more difficult to produce. In addition, when the heat is applied to the resin pipe joint A, the stress of the synthetic resin (the joint body 1 and the union nut 2) may be relaxed and the tube 3 may be easily removed. There is also an advantage that sliding movement in the removal direction is prevented by the action of being caught on the inner surface and performing removal restriction.

  That is, in any case, when the sealing peripheral edge 10 is not pierced into the enlarged diameter portion 3A, the retaining peripheral edge 11 pushes the enlarged diameter portion 3A in the direction of the axis P, thereby causing the straight barrel portion 4B. The press-holding force of the enlarged diameter straight portion 12 by the presser inner peripheral portion 13 is enhanced. For example, as shown in FIG. 2, the corner space portion formed by the pressing surface 11 a and the presser inner peripheral portion 13 is formed by the portion pressed by the retaining peripheral edge 11 in the enlarged diameter portion 3 </ b> A flowing outward in the diameter. There is a possibility that a phenomenon in which the swelled portion 12m is formed by expanding the portion where the restriction on the outer diameter side by the inner circumference portion 13 of the presser foot has been released expands to the outer diameter side.

  As described above, the pressing time difference means provides an effect of further improving both the pressure contact holding force of the tube 3 with respect to the inner cylindrical portion 4 and the pull-out resistance. The union nut 2 of the phantom line shown in FIG. 3 shows when the sealing peripheral edge 10 has reached the diameter expansion change region 9 (specifically, the small diameter side portion of the diameter expansion change region 9). The peripheral edge 11 has already digged into the enlarged diameter change region 9 clearly.

  Moreover, as shown in FIGS. 1 and 2, the circumferential groove m formed by the inner back side of the inner cylinder part 4 and the cover cylinder part 6, and the union nut 2 formed by a fluororesin that can be seen through, An indicator means B that can visually check whether or not the tube 3 is correctly inserted into the inner cylinder portion 4 is configured. That is, the diameter-enlarged portion 3 </ b> A is visually observed on a line (see arrow A in FIG. 2) passing through the valley-like inner peripheral surface 22 on the inner back side of the presser inner peripheral portion 13 and reaching the female screw portion 8. If the tube 3 is in a normal state where the diameter-expanded end portion 3t is not visible, it can be determined that the tube 3 is correctly fitted on the inner cylinder portion 4. If the insertion failure state in which the enlarged diameter portion 3A can be seen and the enlarged diameter end portion 3t can be seen, or the insufficient diameter insertion portion in which the enlarged diameter portion 3A itself cannot be seen, the insertion of the tube 3 is still at the specified amount. In this case, an operation of further pushing the tube 3 is performed until the normal state is visible.

  In the indicator means B, the union nut 2 is formed using a transparent or translucent (milky white or the like) fluororesin so that an object inside thereof can be visually confirmed. The diameter of the union nut 2 is increased by seeing through a line passing through the valley-shaped inner peripheral surface 22 up to the female threaded portion 8 (see arrow A in FIG. 2). The part 3A is relatively clearly visible. On the other hand, the visibility of the enlarged diameter portion 3A is inferior at the part of the presser inner peripheral part 13 which is thicker than the part of the valley-shaped inner peripheral surface 22, and is difficult to see.

  And since the union nut 2 and the cover cylinder part 6 have overlapped in the part of the circumferential groove m in which the edge part of the tube 3 can enter, even if the joint main body 1 can also be seen through, thickness is a valley-shaped inner peripheral surface. In addition to being thicker than the portion 22, a change in the refractive index at the boundary surface due to the overlap between the male screw portion 5 and the female screw portion 8 is also added, so that it is impossible to visually recognize where the enlarged diameter end portion 3 t is located. . In addition, when the joint body 1 is not transparent such as being colored, it is needless to say that the enlarged diameter portion 3A or the enlarged diameter end portion 3t is seen on the inner and inner side of the end wall 15 of the cover cylinder portion 6. I can't.

  Therefore, the union nut 2 was tightened by the function of the indicator means B whether or not a normal state in which the enlarged diameter portion 3A can be seen from the valley-shaped inner peripheral surface 22 and the enlarged diameter end portion 3t cannot be seen. A resin pipe joint A that can be visually confirmed in a later assembled state and that is convenient and excellent in usability can be provided.

  In addition, the presence of the circumferential groove m and the cover tube portion 6 for constituting the indicator means B also provides an effect of functioning as an indicator when the tube 3 is inserted into the inner tube portion 4. That is, it can be confirmed whether or not the amount of insertion into the inner cylinder portion 4 by flaring the tube 3 is a predetermined amount. In other words, it is sufficient that the end portion 3t as the enlarged diameter portion 3A inserted into the inner cylinder portion 4 is located behind the end wall 15, and the quality can be visually determined when the tube 3 is assembled to the inner cylinder portion 4. As an advantage.

  Here, the fitting length to the inner cylinder part 4 in the axis P direction of the enlarged diameter part 3A is L (expanded fitting length L), and from the tip of the inner cylinder part 4 to the end wall 15 of the cover cylinder part 6 If the distance is D (minimum fitting length D) and the maximum tube fitting length of the circumferential groove m is d (adjustment fitting length d), the expanded fitting length L is the minimum fitting length D. It is only necessary to set the length to be equal to or less than the length obtained by adding the adjustment fitting length d to the minimum fitting length D, and this can be known by the indicator means B even after the union nut 2 is tightened. . That is, if D ≦ L ≦ (D + d), the amount of insertion of the tube 3 into the inner cylinder portion 4 is an appropriate amount.

  With the tube 3 inserted into the inner cylinder part 4 without acting the retaining edge 11, a test was conducted to determine how much force the tube 3 would pull out of the inner cylinder part 4 in the direction of the axis P. FIG. 4 shows the result obtained by using the tube 3 having a standard diameter. As an example of a standard diameter, when an inner diameter of 15.8 mm and an outer diameter of 19 mm are used, the pulling force is ○ when L = 5 mm, the pulling force is ◎ when L = 10 mm, and the pulling force is L = 15 mm. The result was that the force was ◎. Here, if the pull-out force is 80 kg or more, the determination is “good”, and if it is 90 kg or more, the determination is “good”. From this, if L is at least 10 mm, good pull-out resistance can be realized, so that L ≧ 10 mm is obtained. In this case, there is no upper limit for L, but if this is the case, the circumferential groove m becomes longer and the axial length of the pipe joint becomes larger.

  By the way, in order to cut the tube 3 with an appropriate length, a cutting tool is used to cut the tube 3 accurately. Usually, however, an ordinary worker usually cuts with a scissor. Often, the cut end is not exactly perpendicular to the tube axis but is cut obliquely. Since it is known from the data that the variation in the axial direction position of the cut surface due to the oblique cut is about 5 mm at the maximum, the substantial depth of the circumferential groove (length in the axial center P direction), that is, d = 5. L ≦ 15 mm as a result, and as a result, 10 mm ≦ Lmm ≦ 15 mm (D = 10 mm, D + d = 15 mm), the cut surface of the tube 3 is inclined, and the length in the axis P direction as a pipe joint is as much as possible. The tube 3 and the inner cylinder part 4 can be fitted in a state having a sufficient pull-out force while considering both of the restraining.

  Therefore, the position of the expanded diameter end portion 3t in the axis P direction is OK as long as it is slightly behind the end wall 15 of the cover tube portion 6 as shown by the solid line in FIGS. The amount of insertion into the inner cylinder portion 4 is OK, and as shown by an imaginary line in FIG. 2, it may be inserted up to a position near the inner back end of the circumferential groove m. Of course, if L <D, the insertion is insufficient, and it goes without saying that the tube 3 is pushed further. The specific lengths of 10 mm and 15 mm mentioned above are only examples, and the actual values take into consideration various conditions such as the material, diameter, thickness, and amount of diameter expansion to the inner cylinder portion 4. It is determined appropriately.

[Another Example]
Although not shown in the drawings, the lower side surface 25 of the protrusion 23 may be a surface that has an overhang-like inclination. Moreover, the protrusion 23 may be configured to have a plurality of circular arcs in the circumferential direction instead of an annular shape, and various changes can be made to the length in the axial center P direction and the length in the radial direction in the cross section.

DESCRIPTION OF SYMBOLS 1 Joint main body 2 Union nut 3 Tube 3A Diameter expansion part 4 Inner cylinder part 4A Tip-cone cylinder part 4B Straight body cylinder part 5 Male thread part 6 Cover cylinder part 8 Female thread part 9 Expansion diameter change area 10 1st press part 11 1st 2 Pressing portion 12 Expanded straight portion 13 Presser inner peripheral portion 23 Protruding portion 24 Upper side surface 25 Lower side surface P Axis

Claims (7)

A diameter of the inner cylindrical portion that is capable of biting into an inner cylindrical portion that can be fitted to the inner tube by expanding the diameter of the end portion of the synthetic resin tube and an outer cylindrical portion of the tube. A joint body made of a synthetic resin provided with a projecting portion formed in a radially outward direction from the straight barrel portion of the body, and a male screw, and
Surrounded by a female screw that can be screwed into the male screw, a first pressing portion for sealing that can act on a small diameter side portion of a diameter expansion change region in the large diameter portion, and the straight barrel portion in the large diameter portion. A union nut made of a synthetic resin, and a presser inner periphery that can be externally fitted to the expanded straight portion.
By unscrewing the union nut in the axial direction of the joint body by screwing the female screw with the male screw in a state where the tube is fitted on the inner tube portion and the enlarged diameter portion is formed. The inner peripheral portion of the presser is press-fitted to the enlarged diameter straight portion surrounded by the protrusion, and the smaller diameter side portion of the enlarged diameter changing region is pressed in the axial direction by the first pressing portion. Resin pipe joint that is configured to be.   The presser inner peripheral portion has no radial gap between it and the enlarged diameter straight portion, and the enlarged diameter straight portion does not cause rotation of the enlarged diameter portion due to tightening of the union nut. The resin pipe joint according to claim 1, wherein the resin pipe joint is press-fitted externally.   The surface on the upper side in the tube insertion direction of the projection is formed on a sloped and inclined surface that increases in diameter toward the lower side in the tube insertion direction, and is formed on an upright surface with the lower side in the tube insertion direction. The resin pipe joint according to claim 1 or 2.   The resin pipe joint according to any one of claims 1 to 3, wherein the protrusion is formed in an annular shape that continues around the axis.   The joint main body is formed with a second pressing portion for retaining that can act on the large-diameter side portion of the diameter-enlargement change region, and the large-diameter side portion of the diameter-enlargement change region by screwing of the union nut The resin pipe joint according to any one of claims 1 to 4, wherein the second pressing portion is pressed in the axial direction.   The state where the pressing of the small-diameter side portion by the first pressing portion is started after the pressing of the large-diameter side portion by the second pressing portion is started by the screwing of the union nut. 5. The resin pipe joint according to 5.   The resin pipe joint according to any one of claims 1 to 6, wherein the joint body and the union nut are both made of a fluororesin.

Images